Four channel headphone

ABSTRACT

An earphone for a four channel headphone has a filling material of light weight and good sound absorbing nature closely fitted inside a unit case. Two cylindrical or conical holes are provided in the filling material in the unit case. A sound generating element is provided at the bottom of each of the holes so that the sound generating element is directed toward the free open end of the unit case and a space is maintained in front of each of the sound generating elements. The free open end of each of the holes is closed by a lid made of a gas permeable material.

Unlted States Patent 11 1 1111 3,836,724

Yamazaki Sept. 17, 1974 [54] FOUR CHANNEL HEADPHONE 3,138,667 6/1964Avedon 179 1 E 3,388,767 6/1968 Wilson 1 181/31 [75] Inventor- Haw!Yamazakl, Tokyo Japan 3,693,752 9/1972 Kinoshita..... 181/31 A [73]Assignee: Chuo Denshi Kogyo Co., Ltd.,

Gunma, Japan Primary Examiner-William C. Cooper Attorney, Agent, orFirmSughrue, Rothwell, Mion, [22] Filed. Dec. 26, 1972 Zinn & Macpeak[21] App]. No.: 318,041

[57] ABSTRACT [30] Foreign Application Priority Data An earphone for afour channel headphone has a fill- Dec. 27, 1971 Japan 46-122648 ingmaterial of light Wight and good Sound absorbing nature closely fittedinside a unit case. Two cylindrical 52 5. CL 179 132 R, 79 0 79 GO orconical holes are provided in the filling material in 51 1m. (:1 H04rl/28 the unit 9989- A Sound generating element is Provided 53 Field fSearch 179 1 E, 5 R, 32 0; at the bottom of each of the holes so thatthe sound 1 1 /D[(} 1 31 B generating element is directed toward thefree open end of the unit case and a space is maintained in front 56] 1References Ci d of each of the sound generating elements. The freeUNITED STATES PATENTS open end of each of the holes is closed by a lidmade of a gas permeable material. 2,775,309 12/1956 V1llchur 181/313,061,690 10/1962 Swinehart 179/1 15.5 R 4 Claims, 3 Drawing FiguresFOUR CHANNEL HEADPHONE BACKGROUND OF THE INVENTION 1. Field of theInvention This invention relates to the construction of an earphone fora four channel headphone to be employed in four channel sterophonicapparatus.

2. Description of the Prior Art An earphone for a four channel headphonehas a construction wherein sound generating elements such as front andrear speakers are equipped in a unit case, and for a pair of cases,ea'chof the sound generating elements reproducing four kinds of sounds suchas the front right'sound, front left sound, rear right sound, and

rear left sound, so that an auditory sensation as in a music hall can beobtained by a listener.

However, when two of the soundgenerating elements are merely encased inthe limited volume of the unit case, the outputsounds generated by thesound generating elements interfere with each other, whereby theresultant sound is not much different from that reproduced from asinglesound generating element. Furthermore, degradation of the soundquality due to the mutual interference of the sound waves cannot beavoided.

SUMMARY OF THE INVENTION The present invention is directed to anearphone employable in a headphone for reproducing the sound ef- BRIEFDESCRIPTION OF TI'IE DRAWINGS FIG. 1 is a front view of one ear side ofan earphone which constitutes an embodiment of the present invention',

FIG. 2 is a sectional view taken along a centerline A-A in FIG. 1; and

FIG. 3 is an exploded perspective view of a headphone constituting asecond embodiment of the present invention.

DESCRIPTION OF PREFERREDEMBODIMENTS In all of the figures, like partsare designated by like reference numerals andcharacters.

In the figures, each earphone comprises an open ended, unit case 1,provided with an ear pad 2, a lid "3 and two plugs 4 and W, all made ofa gas permeable material such as Polyform. A filler 7made of, forinstance, foamed styrol or other resin, paper, or metal, all being oflight weight and of a good sound absorbing nature, is carried by theunit case 1. Through the tiller 7, two holes 5 and 5' are bored.Speakers 6 and6 are placed within the holes 5 and-5', respectively, atintermediate positions or attheir bottoms thereof in a manner such thatthe speakers are directed toward the open ends of the holes 5 and 5'.Suitable distances are maintained between the front surfaces of thespeakers 6 and 6' and the lowersurfacesof the plugs 4 and4,respectively. Furthermore, the filler 7 is placed in the unit case 1 ina sufficiently tight-fit manner to the inner surface of the case 1 thatthe latter will not be resonated to the sound generated from thespeakers.

In order to obtain a good frequency characteristic and optimum soundgenerating quality of the headphone, the shapes of the holes 5 and 5'may be modified so that the diameters thereof are enlarged or reduced inaconical manner. Likewise, the equipped positions of the speakers 6 and6' may also be adjusted to vary the distance between the front surface aand the bottom surface b, respectively, of the filler 7. Furthermore,the plugs 4 and4' made of Polyform or the like may be varied inthickness or in quality, or they may be totally eliminated.

Each earphone according to the present invention is characterized in theabove described construction, and more particularly in the constructionof the holes 5 and 5. That is, the two holes 5 and 5' are provided inthe tiller 7 in a spaced apart relationship, each of the speakers 6 and6 being equipped at an intermediate position between the upper surface aand bottom b, and the holes 5 and 5' are covered, in the propagatingdirection of the sound wave, by lids made of Polyform or the like,whereby the propagating of the sound wave in the surrounding areas canbe prevented, to improve the linearity of the sound wave propagation.The vibration in air within the holes5 and5 can be controlled to improvethe selectivity in the sound waves of different channels. Thus, themutual interference between the sound waves belonging to differentchannels can be substantially reduced, and the selectivity and the tonequality of the sound waves can be remarkably improved.

Furthermore, the two holes. 5 and5' within which speakers 6 and 6' areplaced can act as horns which exaggerate the bass range of the soundwaves.

Thus, according to the present invention, it will be apparent that astereophonic headphone employing dual earphones of this invention fourchannels of superior selectivity and excellent sound reproducible naturecan be obtained in two unit cases of simple construction, of lightweight and at a low cost.

While the invention has been particularly shown and described withreference to preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the spirit and scope of theinvention.

What is claimed is:

1. In a two channel earphone in the form of a unit case and which isemployable in a two unit case, four channel headphone assembly, theimprovement wherein:

each unit case is open at one end,

a mass of light weight sound absorbing filling material closely fits theinterior of said case,

two laterally spaced holes are provided within said material with theholes facing the openend of said case,

a sound generating element is provided within the bottom of each holeand faces the open end thereof,

permeable cover overlies the end of both holes carrying said plugs andis in contact with said plugs.

3. The earphone as claimed in claim 2, wherein: said holes divergeoutwardly from-said sound generating elements.

4. The earphone as claimed in claim 1, wherein: said holes divergeoutwardly from said sound generating elements.

1. In a two channel earphone in the form of a unit case and which is employable in a two unit case, four channel headphone assembly, the improvement wherein: each unit case is open at one end, a mass of light weight sound absorbing filling material closely fits the interior of said case, two laterally spaced holes are provided within said material with the holes facing the open end of said case, a sound generating element is provided within the bottom of each hole and faces the open end thereof, a gas permeable plug of a diameter corresponding to said hole is inserted within the open end of each hole with each hole, being of a thickness and being spaced from a sound generating element carried therein such that the linearity of sound wave propagation is improved and mutual interference between the sound waves of the two channels is reduced.
 2. The earphone as claimed in claim 1 wherein: a gas permeable cover overlies the end of both holes carrying said plugs and is in contact with said plugs.
 3. The earphone as claimed in claim 2, wherein: said holes diverge outwardly from said sound generating elements.
 4. The earphone as claimed in claim 1, wherein: said holes diverge outwardly from said sound generating elements. 